Brake control



June 16, 1925Q E. B. MEAD BRAKH-CONTROL :Filled Jury 14, 1924 PatentedJune 161 11j;

PATENT* OFFICE. i

`f 'EznA B. unan; OF' OTTUMWA, iOWafAssIGNOR rro OTVTU'MWA IRON` `WORKS,Orv OTTUMWAJOWA, A CORPORATION OF IOWA.

BRAKE CONTROL.

Application nie-'a my 14, k1924. "serial No. 725,812." f i' To allwhom tmay 'concer/n: 1'

Beit known that I, EZRA B'. MEAD, a citizen of the United States,residingin Ottumwa, in the county of Wapello 'and State of Iowa, haveinvented a new and useful Improlvement in Brake Controls, of which thefollowing is a specification.

The present invention relates to braking apparatus for minehoists-andthe like, and has more' particular reference to a proportionalpressure brake-control of the general type shown in` my, priorPatentNo.' 1,37 3,195. In the *apparatus of said patent, a control is providedwhich enables the-hoist4 engineer, controlling a cage not visible fromthe control station,to be constantly advised as toV braking conditions,for the reason that the position of the Operating lever and the forcerequired 4to holdsaid lever4 in positionv are proportional to the extentof'braking action. Such a control is highlydesirable when the brakes areapplied lby power, since otherwise he would be withoutvm'eansfofaccurately knowing the? extent of application of the brakes, as'wouldbe' the case ifbraking vwere doneby hands'o that vthe force:exerted'bythe operator in pulling`on"the*handvlever would'fbearl -a'edi'rectpressure relation to brakingv 'conditions `-When the proportionalpressure control of my prior-patent is'em.- ployedfa recognizablerelation ismaint'a'i'ned betweenifthefforce 'exerted l upon vrthe handleverlb'y the operator fand the extent of ,brak- .ing action, and, thiseven though the brakes are appliedby power [instead offby hand,

and thel labor yrequired, is Vthus greatly minimized. ,g Aprimary'obje'ct vofthe present invention isto" provide' a proportional4pressure contrlI accomplishing the above result ,ina dife'ent and, fromcertain aspects, perhaps preferable manner. e

In'` accordance with the invention, raY device" isv employedfforcausingthe operator to feelpressurefuponhis lever at the time the brakes touchthebrake drurnand thereafter linaccordance withthe extent ofbraking'faction, saidv device,'howeve`r, 'having no effect upon andbeing,`iny reality, independent ofthemechanisrn lprovided forcontrolling the power by which 'the brakes are' applied, 1 Any importantadvantage' lof this type of apparatusis itsffrelative sini1 Jlic`it'y,lboth as tocnstfruction andvtleory of operation.l Nli'oisotheii objectsya-ild advantages of the invention will beapparent as it is betterunderstood from the following descript1on,which, taken in connectionwith the accompanying drawings, discloses a preferred embodimentthereof. l Referring to the drawings,

igure lis a diagrammatic view of a brakey coitrol in which my inventioniseinbodied; an v i Fig. 2 is an enlarged sectional view ofthe pressurecontrol valve shown at the lower left-hand 'corner of Fig. 1.y o

In the illustrative embodiment of the invention shown upon the'drawings,the brake (no t shown) is connected to a lever 11,'from which /a weightl2 is suspended above 'a piston cylinder 13, which 'is supplied withfluid pressure by means of a conduit 14, leading from a valve15, whichis controlled by instrumentalities, to be hereinafter described, throughoperation'of a hand lever 16 positioned at the operators station. 'Saidweight 12 isfnormally held in raised position by the pressure inthepiston cylinder 13;` and when ini-this position, the brake isA heldoutof contact with the brake drum. When the pressure is lessened in thecylinder 13, said weight 12 descends, providing' the power by which thebrake is applied. Normallyv the brakeV blocks are held a considerabledistance away from the drum, in order to insure that no rubbing willoccurf during motion of the I hoist when v,braking isV not desired and,consequently, a considerable motion of the weight 12 occurs before saidblocks touch thel drum. Thereafter, the weight continues to move whiletaking up the `compression of the wood`and the springof the levers untilthe weight is hanging completely on the drum. During4 this motion, the'weight' follows the piston :in the cylinder 13 and after the weight-,ishanging on the drum and cannot lower any yurthensaid. piston preferablyhas some, additional motion before reaching the bottoni of its stroke.n,

The lever 16is formed in one with a lever arm 147,'-which is connectedby a rod k18 with a ffulcrum point 1.9 on a horizontal floatinglever 21.Saidl lever 21 connects at22 with4 a stem 23 of a'piston 24', which isvertically lInovablein the bore`25 of Athe valveV 15, Tlieopposite end26 Vof the lever21conneots with Va rod' 27 which is movable with theweight 12 through a suitable form Of conlVhen the leverlismoved .to .theAleft, viewingfllfig. 1,` Lthe point 22 en the lever 21 is moveddownwardly by reason of the tact that the point 26 at the opposite endoit' said lever -is at first held stationary,jand 'this depresses thepiston 241m the cylinder25, opening the valve to exhaust, as Willnowbedescribed.

The thrust cylinder 13, as previously stated, is connected with thevalve 15 by means of a .conduit 1.4i, which conn'nunicates with apassageg28 at :one side'of `saidvalve. An .exhaust port29 is provided.at .the .top of. the, valve.,.so =tl1at when the pistonQi .is lowered,the oil `from thecylinder 13 Imay pass into the upperpartot the chamber25, down throughpassages. 31 `in thepistonF-2et andA -out througlrapipe.32, screwed .intothe bottom closure 33 of the valve and leading todasump, tank. The .topfof vsaid valve is closed by means of astuiiing -boxMA port 35, in the' lowerA part` of vthe. valve, communicates with theVpassage28 .andis supplied from lan accumulator thgrough a passageA 36communicably connectedfwith a pipe. 3.7 V,extending Vfrom the side` ot'Asaidv valve Qppo'site-the= l.conduit 14. "It willl be seen, therefore,.that when the pisto1r2et is -in normaly raised position, as shown inIFig. 2, communication :is .established .between .a source of supply and.that thrust. cylinder 18 holding the Weight12 in raised position.

YAfter :the valve has rbeen .opened -to exhaust, .the Ipiston Iin thethrust cylinder 13 descends, folloWedJoy the weight 12,;fand this lowersthe rod 27 which acts -uponthe floating lever :21 aroundthepoint 419as.a tnlcrum and brings the point-22 andfvalve stem 23 backuptQrmid-pOSitiOn. Continued movement ofthelever. 16 causes .this cycleiofoperation to recur and this may be repeated until .thebrake .Weighthangs .on theidrum and cannot ,be `.lowered.any t'nrther. It :will be..apparentthat .movement .of `the .lever .16 fthe opposite directionwill,tendf toi raise thepoint 22 of thelever r21and therewith theLval.vestem 23, .so .that-the; extent of brakingaction may be accuratelyl.controlled and is inaccolfdance vWith the position-.of the handLlever. y

In myhpriorpatent.hereinbefore referred to, yprovision is made .for.furthervassuring that. `the operator: IWill.be-.constantly` advisedastoQbraking conditions byreason iof'the pressure upon his lever,.wl1icli..ispropor tional .to the extent of 4the, .brakingA action, Thisis accomplishedain .the .apparatusiiofv saidfpatent bymeansof aweight,which-.also Jforms .apart of the control-of t'hezvalve-.by ivlrich the,pressure in, the Y thrust cylndel1 is regulated. Y r'ln .accordance(with the present invention, the .valve controlled in thev mannel"hereinbe'gtore `Adescribed `andgproportional pressure .upon the handlever .is created in manner diagrammatically.illustrated in.':Fig.

1.A l`.heleve1.lfhas an arinftfextending horizontally at-thelower endthereofand in said arm there is provided an adjusting screw 39 adapted,after predetermined. .up- Ward motion of' the arm,`to contact With alever i1 'which is loose on the pivot point 4.2 .oit said lever 16 andcarries at its outer end a Weight 43, Which is supported upon a .coilspringitrresting upon a rigid support 45. The tension of the spring i4and the size ot the Weighte--are so: adjusted. with respect to thespring Vot the llevers 4andbrakc blocks of the lbrake mechanism thatthepres sure .felt unon the ,hanslfl-ever. as. the weight is lifted. fromthespring fifi, is proportional to'ithefextent of the .braking actionand in this manner the operator kept advisedof brak-ing conditionsand.is :enabled to control the hoist accordingly. Normally, the `weight43.rests entirely 'upon thespringzili and the set screwT 39 is out ofcontact With thelever Lll. When' fthe lever. 16 'fhas .been movedsufticiently .to Alower .the Weight 125to the point at. whichv oontactisestablished.betiveenthe brake blocks landthe bra-.ke drum,- the'screw35) comes in `contact \v.ith thecle-.verAl and the operatorbegins .tofeelthe-Weighted; At iirSt, the lifting :of said -Weigl1t.isas sstedbythetension of Athe"spring .44, :but as it is freed. tlieretrom,.it `ismoremnd-niore fe'lt bytheoperator, so thatzhe has the same sensations asthough he were .applying the brake directly. l It. is thought .that theinventionjand -many otV its-.attendant advan't( es {Wi-l1 be understood1from the vforegoing description, .and it` .will be. apparent thatvarious changes may be made iin the form, construction fand-1arrangement.of..the .parts Without departing from, 1the 4.spirit and scope of.theinventiom or. .sacrificing all offfits material advantages, the form...hereinbefore .described .being merely Aa preferred embodimentthereof.

-I.c.lai.m:- rY 1...A-bra`ke control, .comprising imcolnbination Vva`-brake .applying .powerfsourca a brake releasing power source, amanipulativefdevice, la .connection between-.said manipulative .deviceand.V said brake 'releasing power source., -said connectionA being.^.actu. atedibyAv said..device, and means independent of saidconnection and brake releasing power source for ...maintaining arecognizable vrelation .between lthe -orce exerted upon said .device .byan operator andthe extent :of brakingfaction; y

2. A! .brake-.control,. comprisingin fcombination .afbralVapplyingpovver fso'urce, a brake .releasingpower-source, -a manipulative device, a .connectionxbetween said manipulative deviceaandsaidbrake :rele-asing...poWer-:source, :said connection being actuated bysaid-.devicasland means Vindependent of.. said connection and brakereleasing pmver v.source gtor .maintaining a recognizable relationbetween the force eX- erted upon said device by an operator and theextent of braking action, said means comprising a spring-supportedweight asso* ciated with said manipulative device.

3. 'A brake control, `comprising in -combination a brake applying powersource, a brake releasing power source, a manipulative device, aconnection between said manipulative device and saidbrake releasingpower source, said connection being actua-ted by said device, and meansindependent of said connection and brake releasing power source formaintaining a recognizable relation between the force exerted upon saiddevice by an operatorrand the extent of braking acti-on, said meanscomprising a weight rigidly connected with said manipulative device, aspring supporting said weight and a rigid support for said spring.

4. A brake control, comprising in combination a brake applying powersource, a brake releasing power source, a manipulative device, aconnection between said manipulative device and said brake releasingpower source, said connection being actuated by said device, and meanshaving no direct relation to the brake application but causing theoperator to feel pressure upon said manipulative device proportionaltothe extent of the braking action.

5. A brake control, comprising a weight for applying the brakes, fluidpressure means for lifting said weight to release the brakes, meansincluding a hand lever for for applying the brakes, fluid pressurelmeans for lifting said weight to release the brakes, means including ahand lever for controlling the pressure in said last-inentioned means,-and means associated with said lever and having no direct relation tosaid pressure controlling means, whereby the force required to operatethe lever is proportional to the braking action, said means comprising aweight connected with said lever and a resilient supportl for theweight.

7. A brake control, comprising a weight for applying the brakes, apressure cylinder for controlling the position of said weights, a valvefor controlling the pressure in said cylinder, a manipulative de vicefor operating said valve, and means having no effect upon the valve butcre'- ating resistance to the operation of said manipulative deviceproportional to the eX- tent of braking'action. f

, EZRA B. MEAD.

